1
RADIATION PHYSICS & PROTECTION (Q1–25)
1. What is the primary purpose of 25 TAC §289.255?
A. To certify welding inspectors
B. To establish radiation safety requirements and licensing procedures for industrial
radiography
C. To regulate radiographic film disposal
D. To license X-ray machine manufacturers
Answer: B — §289.255(a) establishes radiation safety requirements and
licensing/registration procedures for industrial radiography.
2. Which of the following defines the inverse square law?
A. Intensity is directly proportional to the square of the distance
B. Intensity is inversely proportional to the square of the distance
C. Dose rate decreases linearly with distance
D. Dose rate increases exponentially with distance
Answer: B — Doubling distance reduces intensity to one-fourth.
3. A survey meter reads 120 mR/hr at 2 feet. What is the exposure rate at 4 feet?
A. 60 mR/hr
B. 45 mR/hr
C. 30 mR/hr
D. 15 mR/hr
Answer: C — Doubling distance reduces intensity by a factor of 4 (120 ÷ 4 = 30).
4. What is the annual occupational dose limit for the whole body of an adult
radiographer?
A. 1 rem
B. 3 rem
C. 5 rem
D. 50 rem
Answer: C — DSHS enforces a 5 rem (50 mSv) annual TEDE limit.
5. What is the annual dose limit for the general public?
A. 1 mSv (100 mrem)
B. 5 mSv (500 mrem)
C. 10 mSv (1 rem)
D. 50 mSv (5 rem)
Answer: A — Public dose limits are much lower than occupational limits.
6. What is the lens of the eye dose limit for radiation workers?
A. 15 mSv annually
B. 50 mSv annually
C. 150 mSv annually
, 2
D. 500 mSv annually
Answer: C — Lens of the eye limit is 150 mSv (15 rem) annually.
7. What is the skin and extremity dose limit for workers?
A. 50 mSv annually
B. 150 mSv annually
C. 500 mSv annually
D. 5,000 mSv annually
Answer: C — Skin and extremity limit is 500 mSv (50 rem) annually.
8. What is the ALARA principle?
A. As Low As Radiation Allows
B. As Low As Reasonably Achievable
C. As Limited As Radiation Allows
D. As Low As Regulated Annually
Answer: B — ALARA emphasizes minimizing exposure considering economic and practical
factors.
9. Which isotope is most commonly used for inspecting thick-walled steel components?
A. Iridium-192
B. Cobalt-60
C. Cesium-137
D. Selenium-75
Answer: B — Cobalt-60 emits high-energy gamma rays (1.17 and 1.33 MeV) for thick steel
(2.5–9 inches).
10. What is the half-life of Iridium-192?
A. 30 days
B. 74 days
C. 5.3 years
D. 30 years
Answer: B — Iridium-192 has a half-life of approximately 74 days.
11. What is the half-life of Cobalt-60?
A. 74 days
B. 5.2 years
C. 30 years
D. 10 years
Answer: B — Cobalt-60 half-life is approximately 5.2 years.
12. The thickness of shielding material required to reduce radiation intensity to one-half is
called:
A. Tenth value layer
B. Half-life
, 3
C. Half value layer (HVL)
D. Roentgen value layer
Answer: C — HVL reduces intensity by half.
13. Which material is most effective for shielding gamma radiation?
A. Aluminum
B. Plastic
C. Lead
D. Wood
Answer: C — Dense, high atomic number materials like lead are most effective.
14. A 4 curie Cobalt-60 source produces what dose rate at 1 foot?
A. 5.8 R/hr
B. 23.6 R/hr
C. 58 R/hr
D. 232 R/hr
Answer: C — Cobalt-60 produces approximately 14.5 R/hr per curie at 1 foot (4 × 14.5 = 58).
15. A 4 curie Cobalt-60 source produces what dose rate at 2 feet?
A. 14.5 R/hr
B. 29 R/hr
C. 58 R/hr
D. 116 R/hr
Answer: A — Inverse square law: 58 ÷ 4 = 14.5 R/hr.
16. What is the term for the reduction in intensity when radiation passes through
shielding?
A. Penetration
B. Scatter
C. Attenuation
D. Reflection
Answer: C — Attenuation describes intensity reduction through shielding.
17. A radiation dose received over a long period has what biological effect compared to
the same dose over a short period?
A. Lesser biological effect
B. Same biological effect
C. Greater biological effect
D. No biological effect
Answer: A — Fractionated doses have lesser biological effect.
18. What is a sealed source?
A. Internal contamination
B. Fixed contamination
RADIATION PHYSICS & PROTECTION (Q1–25)
1. What is the primary purpose of 25 TAC §289.255?
A. To certify welding inspectors
B. To establish radiation safety requirements and licensing procedures for industrial
radiography
C. To regulate radiographic film disposal
D. To license X-ray machine manufacturers
Answer: B — §289.255(a) establishes radiation safety requirements and
licensing/registration procedures for industrial radiography.
2. Which of the following defines the inverse square law?
A. Intensity is directly proportional to the square of the distance
B. Intensity is inversely proportional to the square of the distance
C. Dose rate decreases linearly with distance
D. Dose rate increases exponentially with distance
Answer: B — Doubling distance reduces intensity to one-fourth.
3. A survey meter reads 120 mR/hr at 2 feet. What is the exposure rate at 4 feet?
A. 60 mR/hr
B. 45 mR/hr
C. 30 mR/hr
D. 15 mR/hr
Answer: C — Doubling distance reduces intensity by a factor of 4 (120 ÷ 4 = 30).
4. What is the annual occupational dose limit for the whole body of an adult
radiographer?
A. 1 rem
B. 3 rem
C. 5 rem
D. 50 rem
Answer: C — DSHS enforces a 5 rem (50 mSv) annual TEDE limit.
5. What is the annual dose limit for the general public?
A. 1 mSv (100 mrem)
B. 5 mSv (500 mrem)
C. 10 mSv (1 rem)
D. 50 mSv (5 rem)
Answer: A — Public dose limits are much lower than occupational limits.
6. What is the lens of the eye dose limit for radiation workers?
A. 15 mSv annually
B. 50 mSv annually
C. 150 mSv annually
, 2
D. 500 mSv annually
Answer: C — Lens of the eye limit is 150 mSv (15 rem) annually.
7. What is the skin and extremity dose limit for workers?
A. 50 mSv annually
B. 150 mSv annually
C. 500 mSv annually
D. 5,000 mSv annually
Answer: C — Skin and extremity limit is 500 mSv (50 rem) annually.
8. What is the ALARA principle?
A. As Low As Radiation Allows
B. As Low As Reasonably Achievable
C. As Limited As Radiation Allows
D. As Low As Regulated Annually
Answer: B — ALARA emphasizes minimizing exposure considering economic and practical
factors.
9. Which isotope is most commonly used for inspecting thick-walled steel components?
A. Iridium-192
B. Cobalt-60
C. Cesium-137
D. Selenium-75
Answer: B — Cobalt-60 emits high-energy gamma rays (1.17 and 1.33 MeV) for thick steel
(2.5–9 inches).
10. What is the half-life of Iridium-192?
A. 30 days
B. 74 days
C. 5.3 years
D. 30 years
Answer: B — Iridium-192 has a half-life of approximately 74 days.
11. What is the half-life of Cobalt-60?
A. 74 days
B. 5.2 years
C. 30 years
D. 10 years
Answer: B — Cobalt-60 half-life is approximately 5.2 years.
12. The thickness of shielding material required to reduce radiation intensity to one-half is
called:
A. Tenth value layer
B. Half-life
, 3
C. Half value layer (HVL)
D. Roentgen value layer
Answer: C — HVL reduces intensity by half.
13. Which material is most effective for shielding gamma radiation?
A. Aluminum
B. Plastic
C. Lead
D. Wood
Answer: C — Dense, high atomic number materials like lead are most effective.
14. A 4 curie Cobalt-60 source produces what dose rate at 1 foot?
A. 5.8 R/hr
B. 23.6 R/hr
C. 58 R/hr
D. 232 R/hr
Answer: C — Cobalt-60 produces approximately 14.5 R/hr per curie at 1 foot (4 × 14.5 = 58).
15. A 4 curie Cobalt-60 source produces what dose rate at 2 feet?
A. 14.5 R/hr
B. 29 R/hr
C. 58 R/hr
D. 116 R/hr
Answer: A — Inverse square law: 58 ÷ 4 = 14.5 R/hr.
16. What is the term for the reduction in intensity when radiation passes through
shielding?
A. Penetration
B. Scatter
C. Attenuation
D. Reflection
Answer: C — Attenuation describes intensity reduction through shielding.
17. A radiation dose received over a long period has what biological effect compared to
the same dose over a short period?
A. Lesser biological effect
B. Same biological effect
C. Greater biological effect
D. No biological effect
Answer: A — Fractionated doses have lesser biological effect.
18. What is a sealed source?
A. Internal contamination
B. Fixed contamination
